Titanium-Mediated Addition of Grignard Reagents to Acyl Cyanohydrins: Aminocyclopropane versus 1,4-Diketone Formation
作者:Paul Setzer、Gwénaël Forcher、Fabien Boeda、Morwenna S. M. Pearson-Long、Philippe Bertus
DOI:10.1002/ejoc.201301251
日期:2014.1
The 1,2-dianion reactivity of the reagent generated from EtMgBr and titanium isopropoxide was illustrated when N-acyl cyanohydrins were used as substrates (>20 examples), giving both aminocyclopropane derivatives and 1,4-dicarbonyl compounds. When the reaction was performed in diethyl ether, 5-hydroxy-1,4-diketones were the main product. Under specific conditions (use of tetrahydrofuran and a bulky
当 N-酰基氰醇用作底物时(> 20 个实例),说明了由 EtMgBr 和异丙醇钛生成的试剂的 1,2-二价阴离子反应性,得到氨基环丙烷衍生物和 1,4-二羰基化合物。当反应在乙醚中进行时,主要产物为 5-羟基-1,4-二酮。在特定条件下(使用四氢呋喃和庞大的羧基部分),环丙烷衍生物以良好的收率获得。观察到的二分法可以通过五元钛环中间体的开环和非选择性酰基加成来解释。